The PISA one is quite misleading - the "China" scores selectively include only the wealthiest areas of China, which unsurprisingly do very well on the tests. Certainly if a broader swathe of China were included, I'm highly doubtful they would rank anywhere near as high.

Best student performance in math (PISA, 2015)
>> Not at country-level. This is valid only for Shanghai. Quite a feat already but quite a number of countries could cherry-pick their best-performing big city to represent their country and beat China flat-out imho.